A camera module which is used for a cellular phone with a camera, a digital camera, a security camera, or the like has a structure in which, for example, an image sensor such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor), a transparent plate such as glass, a wiring substrate having terminals, a cover body holding the above, a concentrating portion including lenses, a lens barrel, and the like, and a lens holder holding the lenses and the barrel are integrated.
FIGS. 15(a) to (e) illustrate a structure of a camera module of PTL 1. As illustrated in FIG. 15(a), the camera module includes a concentrating portion 20 and an imaging portion 10. The concentrating portion 20 is provided with a lens holder 22 and a lens unit which is fixed to the lens holder 22 and includes a lens 21. The imaging portion 10 is provided with a wiring substrate 11, an image sensor 13 which is mounted on the wiring substrate 11 via an adhesive 12, a transparent plate 17 made of glass, plastics, or the like, and a cover body 14 which covers the wiring substrate 11 and the image sensor. The cover body 14 is mounted on the wiring substrate 11. The image sensor 13 is electrically connected to the wiring substrate 11 with wires 15 or the like. Peripheral part of the transparent plate 17 is fixed to the cover body 14 with an adhesive 16. The lens unit is provided above the image sensor 13 and the transparent plate 17 which are in the imaging portion 10.
An aperture is provided in the center of the cover body 14, and the transparent plate 17 is arranged on the aperture. As a result, an internal space 18 surrounded by the transparent plate 17, the cover body 14, and the wiring substrate 11 is formed in the imaging portion 10.
In a case where the internal space 18 is sealed up, there is a possibility that a gas in the internal space 18 thermally expands in accordance with an increase in temperature and then a crack and the like occurs at a joining part serving as a starting point. Moreover, there is also a possibility that the transparent plate 17 loses transparency due to an influence of a gas or ions which are generated from the adhesive 12, 16, and the like because of a change in temperature or pressure. In the camera module, by providing a ventilation groove G in the cover body 14, the internal space 18 and an outside of the cover body 14 are made to communicate with each other via the ventilation groove G and a gap 19. Note that, a structure of the ventilation groove G is as illustrated in plan view in FIGS. 15(b) to (e).
In this case, when the internal space 18 and the outside of the cover body 14 are made to communicate with each other as described above, there is a possibility that a foreign matter enters the internal space 18 from the outside and the foreign matter adheres to the image sensor 13. In the camera module, a recess part GH is formed by partially digging a bottom of the ventilation groove G deeply as illustrated in FIG. 15(e), and the foreign matter which has entered into the ventilation groove G is trapped by the recess part GH.